Engineering topics
Publications and source records attributed to White, R. L..
A weighted least-squares recursive estimator program is reported for simulating spacecraft orbital position by analyzing earth and sun sensor data. The program uses constant time adjustment for a set of ephemeris data to eliminate intrack error and to improve attitude determination accuracy.
An extended Kalman filter is used to process line-of-sight measurements to stars and known landmarks providing a statistical indication of performance in estimating spacecraft attitude, orbital ephemeris, and the bias drift of a set of three strapdown gyros. The landmark measurements were assumed to have been taken from the imagery of an Earth-observing multispectral scanner. It is shown that filtering of these noisy measurements results in highly accurate estimates of the above parameters. Results are given showing the sensitivity of performance to various system parameters such as star tracker accuracy, errors in the knowledge of landmark position, and number of stars and landmarks processed.